Apparatus in a combustion engine including a device for continually measuring and individually distributing to a plurality of fuel injection valves the amounts of fuel appropriate to the amounts of combustion air

ABSTRACT

What follows is the description of an apparatus for use with a combustion engine which has a plurality of working cylinders with which there are associated a plurality of injection valves. The apparatus includes in combination with a fuel tank, a pump, a fuel control pipe, an amplifying resistance, a differential pressure regulator, a plurality of parallel-connected metering regulators and a plurality of metering resistances, a device which in conjunction with the other stated elements and which is positioned within an air intake channel continually measures and individually distributes to the plurality of fuel injection valves the amounts of fuel appropriate to the amounts of combustion air passing through the intake channel.

United States Patent Zeyns et a1.

APPARATUS IN A COMBUSTION ENGINE INCLUDING A DEVICE FOR CONTINUALLY MEASURING AND INDIVIDUALLY DISTRIBUTING TO A PLURALITY OF FUEL INJECTION VALVES TIIE AMOUNTS OF FUEL APPROPRIATE TO THE AMOUNTS OF COMBUSTION AIR Inventors: Johannes Zeyns, Krauler Elbdeich,

Pappelhof, 2 I-lamburg-Kirchwerder-4; Heinz Enneking, I-Iegholt 32, 2 Hamburg 71, both of Germany Filed: May 11, 1973 Appl. No.: 359,445

Foreign Application Priority Data May 15, 1972 Germany 2223593 US. Cl 123/139 AW; 123/119 R Int. Cl. F02m 39/00 Field of Search 123/139 AW, 119 R References Cited UNITED STATES PATENTS 2/1944 Wunsch 123/139 AW 2,422,808 7/1948 Stokes 123/119 R 2,785,669 3/1957 Armstrong 123/119 R 2,876,758 3/1959 Armstrong 123/139 AW 2,904,026 9/1959 Korte 123/139 AW 2,915,053 12/1959 Armstrong 123/139 AW 3,739,762 6/1973 Jackson 123/139 AW 3,796,200 3/1974 Knapp 123/32 AE Primary Examiner-Charles J. Myhre Assistant Examiner-R. H. Lazarus Attorney, Agent, or FirmEdwin E. Greigg [57] ABSTRACT What follows is the description of an apparatus for use with a combustion engine which has a plurality of working cylinders with which there are associated a plurality of injection valves. The apparatus includes in combination with a fuel tank, a pump, a fuel control pipe, an amplifying resistance, a differential pressure regulator, a plurality of parallel-connected metering regulators and a plurality of metering resistances, a device which in conjunction with the other stated elements and which is positioned within an air intake channel continually measures and individually distributes to the plurality of fuel injection valves the amounts of fuel appropriate to the amounts of combustion air passing through the intake channel.

31 Claims, 6 Drawing Figures PATENTED JUL 2 9 I975 SHEET FIGA APPARATUS IN A COMBUSTION ENGINE INCLUDING A DEVICE FOR CONTINUALLY MEASURING AND INDIVIDUALLY DISTRIBUTING TO A PLURALITY OF FUEL INJECTION VALVES THE AMOUNTS OF FUEL APPROPRIATE TO THE AMOUNTS OF COMBUSTION AIR BACKGROUND OF THE INVENTION This invention relates to apparatus for combustion machines comprising a device for continually measuring the amounts of combustion air drawn in and for continually measuring and individually distributing to a plurality ofinjection valves associated with a plurality of working cylinders the amounts of fuel appropriate to the amounts of combustion air, wherein a measuring device is arranged in the air intake channel to be exposed to the flow of combustion air and alters the flow cross-section of an opening in a fuel control pipe proportionally to the amount of air flowing in the air intake channel, whereupon a control pressure builds up in the fuel control pipe downstream of an amplifying resistance in the pipe, the fuel control pipe extending from a fuel pump by way of the amplifying resistance, thus bringing about a controlled flow of fuel to the measuring and distributing device, and leading back to a fuel tank by way of a differential pressure regulator.

In order to avoid enviromental pollution by combus tion machines, for example Otto engines, it is necessary to supply an optimum fuel-air mixture to each cylinder. This is effected by measuring the air mass flow and, as far as possible, supplying the correct amount of fuel to each cylinder in dependence thereon. A device used for this purpose is described in the German Gebrauchsmuster Utility Specification 6,946,457. The device according to this specification contains a relatively heavy pivoted lever which is mounted at its center of gravity. This impairs the speed of setting and return because of the large sluggish mass of the pivoted lever.

The distribution of the amounts to the separate cylinders is effected in this known device by means of a control slide valve which is mechanically coupled with the pivoted lever. The disadvantage of this however is that the air measuring device cannot be spatially separated from the fuel distributing device. Consequently, this constructional unit is so large that it cannot be incorporated at all or only with difficulty in the engine of many vehicles because of the constricted space in the air intake channel.

Furthermore, it can be very disadvantageous that the fuel supplied from the fuel pump must first flow to this compact unit, in order to be distributed there and to be passed via separate pipes to the injection valves. Having regard to safety against fire in the event of a collision and for the space reasons mentioned above, it is desirable to carry out the distribution of the fuel at spaced, well-protected places by means of shorter pipes.

Distribution of the fuel, particularly during idling, requires extremely high precision, with four parallel control slots according to the aforementioned Utility Specification, since because of the translatory movement of the pivot lever the stroke of the control slide valve is small and thus the control path during idling is extremely small. The conditions are still more onerous because of increased numbers of control slots when one has engines with six or eight cylinders to which fuel must always be supplied under constant pressure, ex-

actly as with the four parallel control slots. The requirements for manufacturing precision and many pipes, which do not comply with fire safety standards, make the device known from the German Utility Specifiction uneconomical, apart from the uncertain operating conditions due to the weight-carrying pivot lever.

Furthermore, an air measuring device for a carburettor is described in US. Patent No. 2,591,356. This device operates with a baffle plate arranged on a pivot lever. The restoring force acting on the pivot lever and the baffle plate is provided by a spring, in addition to a hydraulic restoring force provided as in the aforementioned Utility Specification, namely in such a way that, with increasing air throughput, both the spring force and the hydraulic force are increased and these forces are additive. In this way, no constant sensitivity over the whole range of regulation can be achieved. Clearly, this unsatisfactory division of forces in the device according to the above-identified US. Patent is necessary for valves with a completely predetermined operative characteristics. The valves therefore cannot operate independently of one another.

In the German published patent specification 1,291,934, a regulating device for metering the amount of fuel to be injected into a combustion machine is described, according to which a regulating pressure is derived from a venturi tube and is amplified by means of a piston arranged in a compression cylinder. The fuel is injected by means of this amplified pressure. This device has the disadvantage that the pressure both on the metering side and on the injection side differ, because of the quadratic law of the dependence of pressure upon flow, by a factor of the order of 1,000. Since this range is not mechanically controllable, a separate idling jet for metering the fuel is required, which takes over the measurement in the non-controllable lower range of engine revolutions. Moreover, in this device, uniform distribution to the separate injection valves is not guaranteed.

In another known injection device from the German published patent specification 1,960,148, the flow of fuel branches off downstream of the fuel pump to a fuel pipe which leads to individual injection valves by way of several control valves and several membrane valves, and to a pipe in which are included in the return path to the fuel tank a flow resistance and a regulating member. The fuel flowing into the pipe leading back to the tank thus effects solely the restoring force and is used for correction purposes; in particular it corrects setting faults of the control slide valve and the baffle plate. There is no linear connection between the control fuel flow and the amount of air drawn in The other portion of the flow of fuel which is distributed to the individual injection valves flows firstly on one side of the membranes of the membrane valves to a dimensioning gap of the control slide valve. It then passes downstream of the dimensioning gap to the other side of the membranes of the individual membrane valves, from where it flows on to the injection valves. The difference in pressure between the two sides of the membranes is thus constant, and additional springs provided on the out-flow side see that the outlet openings are kept open to a certain extent. With such a construction, it is not possible to effect the metering of doses to the individual injection valves by means of hydraulic control of the membrane valves. For this, a variable control pressure determined by the amount of air would be necessary, which cannot be achieved with a direct supply of the fuel from the pump. In addition, a spacious separation between the control slide valve and the membrane valves is not possible because of the multiple slot distribution at the slide valve, an a reciprocal influence on the injection valves is unavoidable, i.e., individual additive correction of the individual doses is not possible.

There are thus quite specific disadvantages connected with the known devices which cannot be removed in the manner described above in respect of the operation of various injection valves with different working characteristics, in respect of precision of manufacture, and in respect of fire safety regulations.

In order to enable the use ofinjection valves with various characteristics, with simple manufacturing requirements and with distribution of the fuel to the individual injection valves which is spatially independent of the range of air measurement, it has been proposed in German patent specification 2,134,203 that the baffle plate should by its movements by means of a control slide valve alter the throughput cross-section of a through-opening in a fuel control pipe proportionally to the amount of air flowing in the combustion air channel. There is thus created a fuel control pressure in the fuel pipe after the amplifying resistance, the fuel pipe coming upstream from the fuel pump via the amplifying resistance, thus inducing controlled fuel flow, and leading back to the tank downstream via a differential pressure regulator. With the aid of this fuel control pressure, which is measured between the amplifying resistance and the through-opening, the regulating chambers are controlled by several parallel connected equalpressure regulators which are associated individually with the injection valves. The fuel to be injected is introduced via metering resistances to the metering chambers of the individual equal-pressure regulators which are separated by membranes from the regulating chambers. Corresponding to the pressure distribution between the each regulating chamber and the metering chamber, the membrane between the two is moved relative to an outlet opening, and in dependence on the fuel control pressure. The outlet cross-section to the outlet pipe is thus adjusted in dependence on the fuel control pressure, since the drop in pressure at the laminar metering resistance of each equal-pressure regulator is equal to the drop in pressure at the laminar amplifying resistance.

The construction of this last-mentioned device is such that the amounts of combustion air flowing through the intake nozzles of the machine is distributed uniformly to all cylinders. If this is not ensured, then minor differences in the proportions of the mixture in each cylinder will arise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide apparatus of the kind first mentioned above such that it is possible to make the closing for the individual injection valves individually adaptable to the amounts of combustion air drawn in by the working cylinders whilst maintaining the independence of the injection valves from one another.

This is achieved with apparatus of the kind first mentioned above in which, according to the invention, a reduced control pressure is abstracted downstream of the flow opening which acts as a common force on one side of each of the membranes of parallel-connected metering regulators and is supplemented for the individual membranes by individually adjustable additional forceextending members, while the other side of each of the membranes is subjected to pressure by fuel which is fed thereto through metering resistances and which passes from this side of the membranes downstream of the metering regulators for injection.

By abstracting or taking off the fuel control pressure downstream of the flow opening in the fuel control pipe, there is a fuel pressure at the regulating chambers which is reduced by the same pressure drop Ap relative to the pressure upstream of the flow opening which prevails between the two chambers of the differential pressure regulator. At each metering regulator possibilities are thus created of bringing about quantitive corrections in the doses of fuel given by the individual metering regulators.

According to a preferred feature of the invention, the additional force-exerting members acting on the membranes of the metering regulators are springs, in particular helical springs, whose factor can be adjusted. Helical springs can be dimensioned correctly without difficulties with respect to their force effect, and a particularly fine gradation of the forces applied by them is brought about by their adjustability. Setting screws, for example through the walls of the regulating chambers, can be used for adjustment, with the aid of which the helical springs can be compressed to a greater or lesser extent. The adjustment takes place once when tuning the engine and is then left alone.

According to a further preferred feature of the invention, the resistance value of each individual laminar metering resistance is adjustable. The same effect is obtained by adjusting the laminar metering resistance as is achieved by adjusting the spring force in the metering regulator.

Alternations in the air-fuel mixture ratio in dependence on the throughput can take place by means of additive, multiplicative and quadratic alterations of one of these two flows. According to a preferred feature of the invention, a remote-controlled closure valve is provided in the fuel control pipe downstream of the amplifying resistance and this valve is connected in parallel with a laminar resistance.

By the insertion of the parallel-connected laminar resistance, upon closing of the closure valve, which is formed as an open/close valve, the control pressure in the fuel control pipe upstream of the pressure regulating valve can be altered instantaneously. By thus connecting in circuit a laminar resistance with a multiplicative correction factor B, there is multiplicative alteration in the quantitative fuel flow, which can be represented by the equation 3 a+p (l-l-B)! 7.1 where B is the quantitative flow of fuel;

a is an additive correction factor;

,8 is a multiplicative correction factor;

y is a quadratic correction factor;

I is the quantitative air flow; and

p is a proportionality factor.

The additional laminar resistance provides for a larger pressure drop at the equal-pressure regulators for the individual injection valves. Thus, additional fuel is allowed to pass to the injection valves, which corresponds to enrichment of the fuel mixture. Control of the closure valve can be effected by means of a contact connected to the engine throttle valve, to operate for example when the throttle valve is fully open.

Upon cold starting of the engine, part of the fuel condenses on the cylinder walls and thus leads to a weakened fuel mixture. Also in this case, assistance by means of the closure valve is possible with the aid of a temperature-dependent switch which reacts to low engine temperatures. If this switch effects closing of the closure valve upon low engine temperatures, then the introduction of fuel by way of the laminar resistance due to the artifically increased drop in pressure is increased multiplicatively over the whole working range of the engine.

A further multiplicative aid for the purpose of altering the stoichiometrically desired fuel-air mixture is only possible or is additionally possible by providing assistance at the excess pressure regulator in the fuel control pipe leading back from the differential pressure regulator to the tank. According to a preferred feature of the invention, at the excess pressure regulator, the mechanical force taking effect against the fuel force can be provided by a barometric pressure unit or a barometric pressureand temperature-sensitive unit whose setting member is connected with a membrane of the excess pressure regulator. If the barometric unit is filled with a gas under a suitable pressure, then it reacts in the correct way to pressure and temperature variations of the atmosphere. In order to achieve a suitable spring constant for the unit, an axially acting compression spring may additionally be fitted in the unit.

By means of the barometric unit, the correction factor B of the above equation is altered, whereby a multiplicative variation of the fuel supply again results, and in such a sense that with varying atmospheric conditions, such as during travel in winter with a warm engine or on mountains, a correction of the mixture ratio tending towards a zero carbon monoxide content is produced.

A very simple way of additionally affecting the correction factor B is also possible by a certain construction of the amplifying resistance alone or of the amplifying resistance and the additional laminar resistance connected in parallel with the closure valve. The laminar resistance can in general advantageously comprise a sleeve in which a piston is arranged which consists of two axially spaced piston parts connected together by a rod whose diameter is smaller than the internal diameter of the sleeve and which thus defines an annular gap between itself and the sleeve. To ensure a laminar flow, which is possible over wide regions, an annular gap of about 80 u radial dimension has proved favourable. This laminar resistance can alter the multiplicative correction factor ,8 if the sleeve and the piston-rodpiston unit are made of materials with different coefficients of thermal expansion. The coefficient of thermal expansion of the material of the sleeve should be greater than that of the piston-rod-piston unit. Such a construction of the laminar resistance is achieved for example if the sleeve is of brass and the piston-rodpiston unit of steel. With decreasing temperature, the radial dimension of the annular gap becomes less, and the pressure difference across the laminar resistance increases. This is of course only a correction factor, so that the change in the annular gap radial dimension is only of the order of 1 1,.

According to a further preferred feature of the invention, the resistance value of a laminar resistance can be adjusted in a simple way by arranging a piston with one part of a diameter somewhat larger than that of the other part in a correspondingly widened sleeve bore and adjusting the length determining the resistance by shifting the piston-rod-piston unit in the sleeve.

It can also be desirable to make the enrichment of the fuel-air mixture dependent on the power output. This can be achieved according to a further feature of the invention in that a turbulent resistance with a quadratic characteristic is introduced into the fuel control pipe upstream of the amplifying resistance. This turbulent resistance can consist of an apertured disc. With a low fuel throughput, this turbulent resistance has no effect at all. However, if the fuel throughput increases, then the pressure drop across it rises quadratically, giving a value to 'y in the above equation. The turbulent resistance, with increased fuel throughput, thus for its part additionally increases the pressure drop in the fuel control pipe downstream of the amplifying resistance, whereby a greater supply of fuel to the injection nozzles is achieved.

With some engines it is necessary to provide an additional additive fuel supply, particularly at low engine speeds, e.g. on cold starting. This is achieved according to a further feature of the invention by connecting a bypass pipe into the fuel control pipe upstream of the pressure regulating valve, in which by-pass pipe a regulating valve which is adjustable in dependence on engine temperature is fitted, and the by-pass pipe being connected again to the fuel control pipe downstream of the pressure regulating valve. Operation of the adjustable, additively-acting regulating valve can be effected for example by means of a bimetallic regulator mounted on the engine and sensing the engine temperature. If the adjustable regulating valve is opened with the engine cold, an additional fuel supply flows through the by-pass pipe and decreases the pressure in the fuel control pipe between the amplifying resistance and the pressure regulating valve. In this way an enrichment of the fuel mixture is produced. The additively-acting adjustable regulating valve modifies the factor a in the above-mentioned equation for an additive change in the mixture. It is preferably if the additively-acting regulating valve is opened or closed continuously.

Another possibility arises for similar additive assistance on the air intake side of the apparatus of the invention. A temperature-dependent member for example may be provided in a variable cross-section by-pass bridging the baffle plate. This temperature-dependent member can again be adjustable by means of a bimetallic regulator mounted on the engine and sensing its temperature. If the throughput in the by-pass is decreased by means of a throttle member mounted in it, then the amount of air in the air measuring device increases correspondingly. Thus the fuel supply is increased.

According to a further preferred feature of the invention, a hole in the baffle plate provides a simple additive correction. This hole, like the air by-pass, also produces a modification in the factor a of the abovementioned equation, that is an additive alteration of the fuel-air mixture. The size of the hole in the baffle plate may be adjusted by means of a shutter plate. An alteration in the size of the hole corresponds physically to a movement of the baffle plate on the control slide valve. By means of the hole in the baffle plate, both adjustment of the mixture for idling and also the additive enrichment of the mixture during idle running can be achieved with a single setting member.

BRIEF DESCRIPTION OF THE INVENTION The invention will now be described more fully with the aid of the embodiments illustrated in the accompanying drawings, in which:

FIGS. 1 and 2 show two different forms of the device according to the invention;

FIG. 3 shows a device, for example according to FIG. 2, with the additional components enabling enrichment of the fuel-air mixture;

FIG. 4 shows a laminar resistance for the device according to the invention;

FIG. 5 shows a baffle plate with an aperture which is adjustable in size; and,

FIG. 6 shows an air by-pass pipe which flanks the baffle plate and effects the enrichment of the fuel-air mixture.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment according to FIG. 1, the fuel is pumped by a pump 1 from a tank 3 into a supply pipe 5; it then flows through a laminar amplifying resistance 7 and a pipe 9 to an air measuring device 11.

The air measuring device 11 comprises a control cylinder 12, in which is arranged a control slide valve 13 which is provided with an annular peripheral groove 14. The fuel control pipe 9 discharges into that region of the control cylinder in which is located the annular groove 14 of the control slide valve 13. The fuel supplied from the fuel control pipe 9 consequently fills the annular groove 14. The control cylinder 12 has furthermore an elongate slot 15 which acts as a port through the cylinder wall, which is rectangular in shape, and whose longer axis runs parallel to the longitudinal axis of the cylinder 12. The slot 15 is located at a position where a control edge 17 of the control slide valve 13 covers the slot to a greater or lesser extent on inward and outward travel of the control slide valve 13.

The throughput cross-section at the slot 15 is therefore effectively determined by the position of the control slide valve 13. The amounts of fuel which flow through the port defined by the slot 15 pass at the outlet side to a pipe 21 which leads to a first regulating chamber 23 ofa differential pressure regulator 25. The fuel can flow then from this first regulating chamber 23 through a pipe 27 to an excess pressure regulator 29 which prevents evaporation of the fuel. The fuel passing through the excess pressure regulator 29 then goes via a pipe 31 back to the tank 3.

In the combustion air intake channel 18 there is provided a baffle plate 19 which displaces the control slide valve 13. The baffle plate 19 is struck by the incoming combustion air which exerts a pneumatic force on it. The pneumatic force acting on the baffle plate 19 is opposed by a contrary force, i.e., that exerted by fuel passed under pressure into a pressure chamber 35 adjacent to the end face of the control slide valve 13, this fuel in FIG. 1 being fed to the chamber 35 through a pipe 33 branching from the pipe 21. Since the pressure in the pipe 21, and the control pressure in the fuel control pipe 9, is subject to fluctuations, care must be taken that this fluctuating pressure, together with an additional spring 37 producing a counterforce, exactly counterbalances the hydraulic and mechanical force corresponding to the pneumatic force.

In the embodiment according to FIGS. 2 and 3, the pressure chamber 35 is connected by a pipe 28 to the pipe leading from the differential pressure regulator to the excess pressure regulator. Since here the pressure in the pipe 27 upstream of the excess pressure regulator 29 is constant, the spring 37 can be dispensed with.

In the differential pressure regulator 25, the first regulating chamber 23 is separated from a second regulating chamber 41 by a membrane 39. The control pressure exists in the second regulating chamber 41 and is also present in the fuel control pipe 9, since the second regulating chamber 41 is connected to the fuel control pipe 9 by a pipe 45. A spring 43 acts on the membrane 39 and the magnitude of the force which the spring 43 exerts on the membrane 39 in the differential pressure regulator 25 determines the pressure difference between the chambers 23, 41 or between the fuel control pipe 9 and the pipe 21 on the outlet side of the control slide valve. This ensures that the pressure difference is effective on the dimensioning throughput cross-section of the slot 15.

In order to ensure that the correct excess pressure exists in the pressure chamber 35 under all operating conditions, in the embodiment according to FIG. 1 an auxiliary pipe 47 branches off from the fuel supply pipe 5 supplying the injection valves, and this auxiliary pipe allows a small balancing flow to pass through a throttle valve 49 and thence through a pipe 51 into the pipe system.

In the embodiment according to FIG. 2, an auxiliary pipe 47 likewise branches off from the fuel supply pipe 5, and allows a small balancing flow to pass through the throttle valve 49. However, the pipe 51 downstream of the throttle valve 49 discharges into the pipe 21 upstream of the differential pressure regulator 23. The small balancing flow thus passes into the pipe system and serves to improve the dynamic conditions. Since the pressure in the pipe 27 is constant, in this embodiment no special measures need to be taken to ensure constant pressure in the chamber 35.

In accordance with the changing throughput of fuel at the dimensioning port 15 of the air measuring device 11, pressures arise in the pipes 9 and 21 which change proportionally with the alterations in the amount of fuel flowing through the slot 15. There is nevertheless a pressure difference between the pipes 9 and 21 which is determined by the differential pressure regulator 25. The pressure in the pipe 21 is effective in regulating chambers 52 of metering regulators 53 which are connected in parallel and are each associated with a fuel injection valve in a working cylinder. The fuel required for supplying the injection valves is introduced through the pipe 5 in which a magnetic valve 65 is provided and which is provided with a branch in the region of each metering regulator 53. A laminar metering resistance 55 belongs to each of these parallel branches and is located in a pipe 57 which leads to the metering chamber 59 of the respective metering regulators 53. The metering chambers 59 are separated from the regulating chambers 52 by membranes 61. An inlet aperture 63 of a pipe 66 leading to the associated injection valve seats against each membrane 61. If the membrane 61 rises more because the control pressure has dropped, then the aperture 63 can allow more fuel to passs into the pipe 66 to the injector valve. On the other hand, if the control pressure increases, then the membrane 61 sinks further and the aperture 63 is closed to a greater extent. Thus the supply of fuel to the respective injection valve is then reduced.

The pressure in the pipe 21 is lower then the pressure in the control pipe 9 by an amount p whose magnitude is determined by the spring 43 in the differential pressure regulator 25. In order that the pressure drop in the differential pressure regulator also prevails at the metering regulators 53, a spring 193 is inserted in each of the regulating chambers 52 and exerts a force on the respective membranes 61 which corresponds to the force of the spring 43 on the membrane 39. The springs 193 seat against the chamber walls of the metering regulators which are opposite the membranes 61.

By fitting the spring 193, the metering of fuel to the individual working cylinders is tailored individually to the amount of combustion air being drawn in by the respective individual working cylinders. Each of the springs 193 can be supported on a counterpressure plate 197 which seats on the regulating chamber wall 195. By means of an adjustment screw 199 the counterpressure plate 197 can be screwed into or out of the respective regulating chamber 52. Correspondingly, the force exerted by the spring 193 on the membrane 61 is altered. In this way, the amount of fuel required for the amount of combustion air which is drawn in by the individual working cylinders is matched by this additive correction.

The metering resistances 55 and the amplifying resis tance 7 are laminar resistances, and the metering resistances 55 can be adjusted as to their resistance value. By adjusting the laminar metering resistances 66 the me tering of fuel to the separate injection valves can still similarly be individually and proportionally adjusted.

In the fuel control pipe 9, a valve 67 (FIG. 3) is arranged downstream of the amplifying resistance 7 and is connected in parallel with a laminar resistance 7a. The valve 67 is remotely controllable, either by the accelerator pedal 68 through a switch 69, or by a bimetallic switch 70a arranged on the engine 70. By means of the accelerator pedal 68, the valve 67 is actuated as an on/off valve, and is closed when the accelerator pedal 68 is almost completely depressed position of the acclerator pedal 68, which corresponds to the throttle valve being fully open, the accelerator pedal 68 actuates the switch which effects the closing of the valve 67. Thus, the additional laminar resistance 7a is connected into the fuel control pipe 9 and lowers the pressure in the fuel control pipe 9. The reduction of the pressure has a multiplicative effect in a sense to produce an enrichment of the fuel-air mixture so that, with the acclerator pedal 68 fully depressed, the power of the engine 70 can be increased. The bimetallic switch 70a similarly controlling the valve 67 is mounted directly on the engine 70 and monitors its temperature. When the engine is cold, it closes the valve 67, so that enrichment occurs for cold starting. Both with the accelerator pedal 68 fully depressed and with switching of the valve 67 by means of the bimetallic switch 70a, the multiplicatively acting correction factor ,3 of the fuel-air mixture equation is altered.

The multiplicative alteration of the amount of fuel metered to the air can be achieved in a similar way by a barometric bellows 71 which acts upon the membrane of the excess pressure regulator 29. The barometric bellows 71 can be filled with a gas of suitable pressure and suitable composition in such a manner that it regulates the mixture with pressure and temperature changes, for example during travel at high altitude, or in winter conditions, and so on, so that the carbon monoxide content is as near to zero as possible. The multiplicative alteration of the amount of fuel present in the fuel-air mixture can be readily adjusted to a satisfactory value by means of this barometric bellows acting on the excess pressure regulator. Pre-setting of the barometric bellows can be effected with the aid of a compression coil spring 73 acting in the direction of expansion of the bellows.

In FIG. 4 a laminar resistance is illustrated which on the one hand is adjustable as to its magnitude and which on the other hand is dependent on temperature. This laminar resistance consists of a sleeve 171 in which a unit, consisting of a piston 173, a piston rod 175 and a further piston 177, is axially movable. The pistons 173 and 177 are fitted in the sleeve 17] in a fluid-tight sealed manner. The external diameter of the piston 177 and the internal diameter of the sleeve part 179 in which the piston 177 is arranged are slightly greater than the external diameter of the piston 173 and the internal diameter of the sleeve part 181. The piston rod 175 has only a slightly smaller external diameter than the sleeve wall 181 which encircles the outer surface 183 of the piston rod. Between the walls 181 and 183 there is formed an annular gap 191 whose radial dimension is of the order of 80a.

The two pistons 173 and 177 are bored through at 185 and 185. Fuel can flow into and out of the bores 185 and 185. Transverse channels 187 and 187' extend from the internal ends of the bores 185 and 185 to annular grooves 189 and 189. The fuel flows through the one annular groove 189 into the annular gap 191 representing a laminar section, and the fuel then flows out through the other annular groove 189' via the transverse channels 187' and the bore 185'.

The sleeve 171 is longer than the piston-rod-piston unit. For this reason, the piston-rod-piston unit is axially movable in the sleeve 171. Because of this ability to move, the resistance in the annular gap 191 forming the laminar section can change. The flow-path length for the fuel between the left-hand annular groove 189 and the transition into the sleeve part with the larger internal diameter, i.e., the point 192 in the right-hand half of the laminar resistance, determines the magnitude of the laminar resistance. If the correction made by the bellows 71 in order to correct temperature errors is dispensed with, then the errors which arise through temperature changes and the change of the air density associated therewith are compensated by this laminar resistance, if the sleeve and the piston-rodpiston unit are made of two materials with two suitably different coefficients of thermal expansion. Brass for example is suitable as a material for the sleeve, while the piston-rod-piston unit can be made of steel. Of course, other combinations of metals can also be used. If, for example, the ambient temperature drops, then the density of the air rises. The fuel-air mixture is thus made weaker Correction is made possible in that the different coefficients of thermal expansion in this particular case reduce the annular gap between the rod and the sleeve. Thus the pressure in the control pipe 9, 45 drops, and more fuel is injected into the cylinders. The correction factor B for the multiplicative alteration 11 of the fuel-air mixture is affected by the variable laminar resistance.

A turbulent resistance 75, illustrated in FIG. 3, which is formed as an apertured plate, can be used to vary the amount of fuel with respect to the amount of air. This turbulent resistance 76 is almost without effect long as the flow of fuel through it is only small. If the flow of fuel increases, then its pressure drop increases qua dratically, Correspondingly, if the flow of fuel decreases, the pressure in the fuel control pipe 9 also drops. By means of the turbulent resistance 75, strengthening or enrichment of the fuel-air mixture with greater amounts of fuel can be effected in dependence on the engine power.

An additional enrichment and thus a correction to the correction factor a can be desirable particularly when starting an engine from cold. This enrichment is brought about, as shown in FIG. 3; with the aid of a bypass pipe 77 in which is fitted a regulating valve 79. This regulating valve 79 is controlled by a bimetallic regulator 70b which is arranged on the engine 70. When the engine is cold, the regulating valve 79 is open, and it closes increasingly with the increasing engine temperature. By positioning the by-pass pipe 77 between the fuel control pipe 9 and the pipe 21 leading back to the tank downstream of the pressure regulating valve 11, with the engine cold part of the fuel flows through the pressure regulating valve 11 to the pipe 21, whereupon the pressure in the fuel control pipe 9 drops. With decreasing pressure in the fuel control pipe, however, the pressure drop at each of the equal pressure metering regulators 53 increases so that the metering apertures 63 open further.

With a change of the baffle plate 19, shown in FIG. 5, a further additive variation in the ratio of fuel to air can be brought about. A hole 81 is provided through the baffle plate and can be closed to a greater or lesser degree by means of a plate 83 which is mounted at 85. Alteration of the flow cross-section of the hole 81 is physically equivalent to displacement of the baffle plate 19 on the control slide valve 13. By means of this displacement, an idling mixture adjustment can be carried out. The same effect is achieved if the plate 83 is displaced by the desired amount and is then locked in position by a screw 87 fitted at the pivot point 85.

By means of the hole 81 in the baffle plate and by means of the plate 83, the mixture can also be adjusted during idle running. With increased closing of the hole 81, the additive enrichment of the mixture during idling is increased. By means of the plate 82 alone, both idling mixture adjustment and enrichment of the mixture during idling can thus be regulated.

In the same way as enrichment of the mixture can be brought about by changes at the air intake side by means of the hole 81 in the baffle plate, changes at the air intake side can also be brought about by an by-pass 89, illustrated in FIG. 6, which bridges the baffle plate 19. An adjustable flap 91 to vary the throughput crosssection is arranged in the air by-pass 89 and can moreover be adjusted by the bimetallic regulator 70a or 70b. The bimetallic regulator measures the engine temperature and opens the air by-pass 89 when the engine temperature increases.

All correction members incorporated in the device alone or in combination and providing for the most varied conditions, set up operating states for the engine which are suited to all working conditions. The additional laminar resistance 7a and the barometric bellows 71 alter a multiplicative correction factor B, the turbulent resistance 75 alters a quadratic correction factor 7, and the regulating valve 79 as well as the hole 81 and the by-pass pipe 89 alter the additive correction factor a which alters the mixture, all these factors being present in the above-mentioned equation for the fuel-air ratio. The means used are of a simple kind and can be installed in the device without major expense.

What is claimed is:

1. In combustion engines having a plurality of working cylinders, an air intake channel and a plurality of injection valves associated therewith, an apparatus comprising:

a. a device arranged in the air intake channel to be exposed to the flow of combustion air for continually measuring the amounts of combustion air drawn in and for continually measuring and individually distributing to the plurality of injection valves the amounts of fuel appropriate to the amounts of combustion air;

b. a fuel tank;

c. a fuel control pipe connected between said fuel tank and said device, said fuel control pipe having an opening, the flow cross section of said opening being altered by said device proportionally to the amount of air flowing in the air intake channel;

d. a fuel pump for delivering fuel through said fuel control pipe to said device;

e. an amplifying resistance connected within the flow path defined by said fuel control pipe with a control pressure being built up in said fuel control pipe downstream of said amplifying resistance by the alteration of said opening, thus bringing about a controlled flow of fuel to said device;

f. a differential pressure regulator connected to said fuel control pipe, said device and said fuel tank;

a plurality of parallel-connected metering regulators each including a membrane and an adjustable additional force-exerting member on one side of said membrane, said metering regulators being connected to said device and said fuel control pipe, wherein a reduced control pressure is abstracted downstream of said opening which acts as a common force on one side of each of said membranes, said reduced control pressure being supplemented by said forceexerting members; and

h. a plurality of metering resistances, one for each of said metering regulators, each said metering resistance being connected to its respective metering regulator to the other side of the membrane of that metering regulator and to said fuel control pipe, said other side of each metering regulator being subjected to pressure by fuel which is fed thereto by said fuel pump and through a respective metering resistance, said fuel passing from this side of said membranes downstream of the metering regulators for injection.

2. Apparatus according to claim 1, in which the additional force-exerting members acting on the membranes of the metering regulators are springs.

3. Apparatus according to claim 1, in which the force on the membranes is adjustable by helical springs acting on the membranes.

4. Apparatus according to claim 3, in which each helical spring is supported, adjacent to a regulator chamber wall which faces the membrane, on a plate which is adjustable by means of a setting screw in the direction towards the membrane.

5. Apparatus according to claim 1, in which the metering resistances are laminar resistances and in which the resistance value of each individual laminar metering resistance is adjustable.

6. Apparatus according to claim 1, in which a magnetic valve is provided in a fuel pipe which serves as a feed pipe to the injection valves and which is common to the metering regulators.

7. Apparatus according to claim 1, in which the measuring device comprises a baffle plate mounted directly on a control slide valve which co-operates with said flow opening.

8. Apparatus according to claim 1, in which a remotely-controlled closure valve is arranged in the fuel control pipe downstream of the amplifying resistance and is connected in parallel with a laminar resistance.

9. Apparatus according to claim 8, in which the closure valve is the fuel control pipe is coupled to the accelerator pedal and is closed when the accelerator pedal is substantially fully depressed.

10. Apparatus according to claim 8, in which the closure valve is adjustable by means of a bimetallic switch which is mounted on the engine.

11. Apparatus according to claim 1, further comprising an excess pressure regulator in the fuel control pipe leading back from the differential pressure regulator to the fuel tank, wherein a mechanical force acts on a membrane in the excess pressure regulator against the force of the fuel and is provided by a barometric pressure unit or a pressureand temperature-sensitive barometric unit having a setting member connected to the membrane of the excess pressure regulator.

12. Apparatus according to claim 11, in which the barometric unit is filled with gas.

13. Apparatus according to claim 11, in which a compression spring acting in the direction of expansion is arranged in the barometric unit.

14. Apparatus according to claim 1, in which the amplifying resistance connected in parallel with a closure valve downstream of the amplifying resistance, comprises a sleeve in which is arranged a unit consisting of two pistons which are axially spaced and which are connected by a rod whose diameter is smaller than the internal diameter of the sleeve and which defines an annular gap between itself and the sleeve.

15. Apparatus according to claim 14, in which the annular gap has a radial dimension which produces a laminar flow therethrough, for example, of the order of 80 1..

16. Apparatus according to claim 14, in which the sleeve and the piston-rod-piston unit are of materials with different coefficients of thermal expansion.

17. Apparatus according to claim 16, in which the coefficient of thermal expansion of the sleeve material is greater than that of the material of the piston-rodpiston unit.

18. Apparatus according to claim 16, in which the sleeve is of brass and the piston-rod-piston unit is of steel.

19. Apparatus according to claim l4, in which one of said pistons has a diameter which is somewhat larger than that of the other piston. said larger diameter piston being arranged in a correspondingly enlarged sleeve bore. with the piston-rod-piston unit being displaceable in the sleeve.

20. Apparatus according to claim 1, in which the amplifying resistance and an additional laminar resistance connected in parallel with a closure valve downstream of the amplifying resistance, comprises a sleeve in which is arranged a unit consisting of two pistons which are axially spaced and which are connected by a rod whose diameter is smaller than the internal diameter of the sleeve and which defines an annular gap between itself and the sleeve.

21. Apparatus according to claim 1, in which a turbulent resistance with a quadratic characteristic is pro vided in the fuel control pipe upstream of the amplifying resistance.

22. Apparatus according to claim 21, in which the turbulent resistance is an apertured plate.

23. Apparatus according to claim 1, in which a bypass pipe is connected into the fuel control pipe upstream of the measuring device and a regulating valve which is adjustable in dependence on the engine temperature is inserted in the by-pass pipe, the by-pass pipe being also connected downstream of the measuring device to the fuel control pipe.

24. Apparatus according to claim 23, in which the regulating valve is controlled by a bimetallic regulator mounted on the engine and sensing its temperature.

25. Apparatus according to claim 24, in which the bimetallic regulator continuously adjusts the regulating valve.

26. Apparatus according to claim 7, in which a member which is dependent on engine parameters is arranged in an air by-pass bridging the baffle plate and is arranged to vary the flow cross-section of the air bypass.

27. Apparatus according to claim 26, in which the member is a valve which is controlled by a bimetallic switch.

28. Apparatus according to claim 7, in which a hole is provided through the baffle plate.

29. Apparatus according to claim 28, in which the size of the hole is determined by an adjustable shutter plate.

30. Apparatus according to claim 7, in which a pressure chamber is provided in a control cylinder in which the slide valve is displaceable, the pressure chamber being at the end of the cylinder remote fromthe baffle plate and being defined by one end of the control slide valve, and the pressure chamber being connected to a fuel pipe in which the fuel is under pressure.

31. Apparatus according to claim 30, in which the fuel pressure in the fuel pipe leading to the pressure chamber is substantially constant. 

1. In combustion engines having a plurality of working cylinders, an air intake channel and a plurality of injection valves associated therewith, an apparatus comprising: a. a device arranged in the air intake channel to be exposed to the flow of combustion air for continually measuring the amounts of combustion air drawn in and for continually measuring and individually distributing to the plurality of injection valves the amounts of fuel appropriate to the amounts of combustion air; b. a fuel tank; c. a fuel control pipe connected between said fuel tank and said device, said fuel control pipe having an opening, the flow cross section of said opening being altered by said device proportionally to the amount of air flowing in the air intake channel; d. a fuel pump for delivering fuel through said fuel control pipe to said device; e. an amplifying resistance connected within the flow path defined by said fuel control pipe with a control pressure being built up in said fuel control pipe downstream of said amplifying resistance by the alteration of said opening, thus bringing about a controlled flow of fuel to said device; f. a differential pressure regulator connected to said fuel control pipe, said device and said fuel tank; a plurality of parallel-connected metering regulators each including a membrane and an adjustable additional forceexerting member on one side of said membrane, said metering regulators being connected to said device and said fuel control pipe, wherein a reduced control pressure is abstracted downstream of said opening which acts as a common force on one side of each of said membranes, said reduced control pressure being supplemented by said forceexerting members; and h. a plurality of metering resistances, one for each of said metering regulators, each said metering resistance being connected to its respective metering regulator to the other side of the membrane of that metering regulator and to said fuel control pipe, said other side of each metering regulator being subjected to pressure by fuel which is fed thereto by said fuel pump and through a respective metering resistance, said fuel passing from this side of said membranes downstream of the metering regulators for injection.
 2. Apparatus according to claim 1, in which the additional force-exerting members acting on the membranes of the metering regulators are springs.
 3. Apparatus according to claim 1, in which the force on the membranes is adjustable by helical springs acting on the membranes.
 4. Apparatus according to claim 3, in which each helical spring is supported, adjacent to a regulator chamber wall which faces the membrane, on a plate which is adjustable by means of a setting screw in the direction towards the membrane.
 5. Apparatus according to claim 1, in which the metering resistances are laminar resistances and in which the resistance value of each individual laminar metering resistance is adjustable.
 6. Apparatus according to claim 1, in which a magnetic valve is provided in a fuel pipe which serves as a feed pipe to the injection valves and which is common to the metering regulators.
 7. Apparatus according to claim 1, in which the measuring device comprises a baffle plate mounted directly on a control slide valve which co-operates with said flow opening.
 8. Apparatus according to claim 1, in which a remotely-controlled closure valve is arranged in the fuel control pipe downstream of thE amplifying resistance and is connected in parallel with a laminar resistance.
 9. Apparatus according to claim 8, in which the closure valve is the fuel control pipe is coupled to the accelerator pedal and is closed when the accelerator pedal is substantially fully depressed.
 10. Apparatus according to claim 8, in which the closure valve is adjustable by means of a bimetallic switch which is mounted on the engine.
 11. Apparatus according to claim 1, further comprising an excess pressure regulator in the fuel control pipe leading back from the differential pressure regulator to the fuel tank, wherein a mechanical force acts on a membrane in the excess pressure regulator against the force of the fuel and is provided by a barometric pressure unit or a pressure- and temperature-sensitive barometric unit having a setting member connected to the membrane of the excess pressure regulator.
 12. Apparatus according to claim 11, in which the barometric unit is filled with gas.
 13. Apparatus according to claim 11, in which a compression spring acting in the direction of expansion is arranged in the barometric unit.
 14. Apparatus according to claim 1, in which the amplifying resistance connected in parallel with a closure valve downstream of the amplifying resistance, comprises a sleeve in which is arranged a unit consisting of two pistons which are axially spaced and which are connected by a rod whose diameter is smaller than the internal diameter of the sleeve and which defines an annular gap between itself and the sleeve.
 15. Apparatus according to claim 14, in which the annular gap has a radial dimension which produces a laminar flow therethrough, for example, of the order of 80 Mu .
 16. Apparatus according to claim 14, in which the sleeve and the piston-rod-piston unit are of materials with different coefficients of thermal expansion.
 17. Apparatus according to claim 16, in which the coefficient of thermal expansion of the sleeve material is greater than that of the material of the piston-rod-piston unit.
 18. Apparatus according to claim 16, in which the sleeve is of brass and the piston-rod-piston unit is of steel.
 19. Apparatus according to claim 14, in which one of said pistons has a diameter which is somewhat larger than that of the other piston, said larger diameter piston being arranged in a correspondingly enlarged sleeve bore, with the piston-rod-piston unit being displaceable in the sleeve.
 20. Apparatus according to claim 1, in which the amplifying resistance and an additional laminar resistance connected in parallel with a closure valve downstream of the amplifying resistance, comprises a sleeve in which is arranged a unit consisting of two pistons which are axially spaced and which are connected by a rod whose diameter is smaller than the internal diameter of the sleeve and which defines an annular gap between itself and the sleeve.
 21. Apparatus according to claim 1, in which a turbulent resistance with a quadratic characteristic is provided in the fuel control pipe upstream of the amplifying resistance.
 22. Apparatus according to claim 21, in which the turbulent resistance is an apertured plate.
 23. Apparatus according to claim 1, in which a by-pass pipe is connected into the fuel control pipe upstream of the measuring device and a regulating valve which is adjustable in dependence on the engine temperature is inserted in the by-pass pipe, the by-pass pipe being also connected downstream of the measuring device to the fuel control pipe.
 24. Apparatus according to claim 23, in which the regulating valve is controlled by a bimetallic regulator mounted on the engine and sensing its temperature.
 25. Apparatus according to claim 24, in which the bimetallic regulator continuously adjusts the regulating valve.
 26. Apparatus according to claim 7, in which a member which is dependent on engine parameters is arranged in an air by-pass bridging the baffle plate and is arranged to vary the flow cross-section of the Air by-pass.
 27. Apparatus according to claim 26, in which the member is a valve which is controlled by a bimetallic switch.
 28. Apparatus according to claim 7, in which a hole is provided through the baffle plate.
 29. Apparatus according to claim 28, in which the size of the hole is determined by an adjustable shutter plate.
 30. Apparatus according to claim 7, in which a pressure chamber is provided in a control cylinder in which the slide valve is displaceable, the pressure chamber being at the end of the cylinder remote from the baffle plate and being defined by one end of the control slide valve, and the pressure chamber being connected to a fuel pipe in which the fuel is under pressure.
 31. Apparatus according to claim 30, in which the fuel pressure in the fuel pipe leading to the pressure chamber is substantially constant. 